Clavia Nord Lead A1 by Poupou
The A1 is a very fun beast to use. It can produce a very wide range of sounds that fit in a multitude of genres. I would say that getting really amazing unique sounds from scratch on it requires some solid experience/knowledge about synthesis (but isn't that the same on any synth ). You might find disappointing demos out there, but chances are they are not due to the limitations of the machine itself.
The synth's architecture is rather unconventional. It uses an oscillator section, which appears to feature a single oscillator, at first. It does, in fact, present multiple oscillators, which you need to access from the "osc config" knob. You then get a bunch of classic oscillator configurations which you can modify through the "osc ctrl" knob. For example, you can set the configuration to be sync, so that your initial waveform is synced, or you could choose the detune configuration to have another identical oscillator to your first one, but with adjustable pitch. You also have a nice set of configurations that allow FM and AM synthesis (not on a super deep level, however. Only a single operator is available).
You can produce pretty much any kind of sound you would want to. The 4 separate timbers, present on most Nords, are also super useful. The build is super solid, just like other Nord products. There is no aftertouch on this keyboard, which is worth taking into consideration before buying.
It presents a randomizer button which randomizes all the parameters of the synth. I find this really cool to get some new original sounds.
Overall, a very polyvalent, fun and useful machine. It'll keep you occupied for years!